(THE ISSUE)
As of the April 14, 2026 Windows Update (KB5083769), Microsoft has fundamentally changed how Remote Desktop handles clipboard and drive redirection to combat RDP-based phishing attacks.
Starting with the April 2026 update, if you use .rdp files to connect, Windows now defaults all resource redirections (including the Clipboard) to Off.
The Symptom: You connect as usual, but copy-paste doesn't work.
The Cause: A new security dialog appears when you launch the connection. If you click "Connect" without looking closely, it may be blocking the clipboard by default.
(MANUAL METHOD)
When the new "Connection Security" warning pops up, you must manually check the box
for Clipboard (and Drives if you want to copy files) before clicking Connect.
(ADMIN LONG TERM FIX)
No, the community has not found a way to "automate" checking those boxes via a batch script. Microsoft intentionally hardcoded this new prompt so that if a connection is Unsigned / Unknown, the resource boxes (Clipboard, Drives) are forced OFF, and the system physically requires a human to click them. Furthermore, unsigned connections are no longer allowed to "remember" your choices.
However, sysadmins have shared the "escape hatch." Microsoft quietly included a registry key specifically for IT departments whose workflows were broken by this update. This key reverts the security prompt back to the old version, bypassing the new "unchecked by default" behavior entirely.
The Sysadmin Fix: The Rollback Registry Key
If you have Administrator rights on your local PC, you can disable the new 2026 warning dialog and return it to the legacy behavior where clipboard redirection just works.
You need to run this command in a Command Prompt opened as Administrator:
(REG KEY LONG TERM FIX)
reg add "HKLM\Software\Policies\Microsoft\Windows NT\Terminal Services\Client" /v "RedirectionWarningDialogVersion" /t REG_DWORD /d 1 /f